Method of advancing a continuous mining machine and apparatus therefor

ABSTRACT

A continuous miner having improvements therein for enabling the same to be advanced in a coal seam having a shortwall face extending concavely arcuate from one side wall defining one end thereof to another side wall defining the other end thereof about an axis spaced outwardly thereof in a cycle which includes positioning the continuous miner adjacent one end of the arcuate face of the coal seam, effecting a pivotal movement of the continuous miner across the face to a position adjacent the other end thereof about an axis spaced from the axis of the face both in a direction toward the face and in a direction toward said other end thereof to progressively remove a section of coal from the seam which extends inwardly of the face a distance which increases progressively in the direction of movement across the face and to progressively define an advanced face which extends concavely arcuate about said spaced axis of pivotal movement and then effecting a pivotal movement of the continuous miner across the advanced face from said other end to a position adjacent said one end about an axis spaced from the axis of said advanced face both in a direction toward the advanced face and in a direction toward said one end thereof to progressively remove a section of coal from the seam which extends inwardly of the advanced face a distance which increases progressively in the direction of movement across the advanced face and to progressively define a further advanced face which extends concavely arcuate about the spaced axis of the last mentioned pivotal movement.

Tlnite ttes atent 1191 lsagowslti 1 .llan.7,1975

[ METHOD OF ADVANCING A CUNTHNUOUS MINING MACHINE AND APPARATUS THEREFOR[75] Inventor: Joseph V. Lagowski, Madscott, W.

[73] Assignee: Wilcox Manufacturing Co. Inc,

Raleigh, W. Va.

[22] Filed: May 30, 1973 [21] Appl. No.: 365,061

Primary Examir1erErnest R. Purser Attorney, Agent, or FirmCushman, Darby& Cushman [57] ABSTRACT A continuous miner having improvements thereinfor enabling the same to be advanced in a coal seam having a shortwallface extending concavely arcuate from one side wall defining one endthereof to another side wall defining the other end thereof about anaxis spaced outwardly thereof in a cycle which includes positioning thecontinuous miner adjacent one end of the arcuate face of the coal seam,effecting a pivotal movement of the continuous miner across the face toa position adjacent the other end thereof about an axis spaced from theaxis of the face both in a direction toward the face and in a directiontoward said other end thereof to progressively remove a section of coalfrom the seam which extends inwardly of the face a distance whichincreases progressively in the direction of movement across the face andto progressively define an advanced face which extends concavely arcuateabout said spaced axis of pivotal movement and then effecting a pivotalmovement of the continuous miner across the advanced face from saidother end to a position adjacent said one end about an axis spaced fromthe axis of said advanced face both in a direction toward the advancedface and in a direction toward said one end thereof to progressivelyremove a section of coal from the seam which extends inwardly of theadvanced face a distance which increases progressively in the directionof movement across the advanced face and to progressively define afurther advanced face which extends concavely arcuate about the spacedaxis of the last mentioned pivotal movement.

13 Claims, 13 Drawing Figures PATEHTEDJAN N975 3 858 94 sum 20! s [IOUFIG.2D

METHOD OF ADVANCING A CONTINUOUS MINING MACHINE AND APPARATUS THEREFORThis invention relates to coal mining and more particularly toimprovements in the method and apparatus for advancing continuous miningmachines in a coal seam.

While the principles of the present invention have applicability tocontinuous mining machines embodying other types of cutters, theinvention has been particularly developed for applicability withcontinuous mining machines of the dual auger type. Machines of this typeare commercially manufactured and sold under the trademark Wilcox MARK20 by the Wilcox Manufacturing Co. of Beckley, West Virginia. A similarmachine, designated the 100L, is manufactured by Jeffrey ManufacturingCompany of Columbus, Ohio. The basic construction and mode of operationof these machines is disclosed in Wilcox US. Pat. No. 3,026,098. (Seealso related U.S. Pat. Nos. 3,282,403; 3,305,268; and 3,306,667.)

Machines of the dual auger type, as the name implies, employ two augersas the means for removing the coal from the seam. The augers areoppositely pitched with respect to each other and are mounted on theframe of the machine in forwardly disposed relation with their axesextending generally horizontally forwardly in horizontally spacedparallel relation. The augers are mounted for power driven rotation inopposite directions and for independent vertical movement, as by apivotal action about an axis parallel to the axis of rotation. Eachauger includes a pair of helical blades having a series of cutting teethatthe forward end thereof and a series of teeth extending outwardly ofthe periphery thereof in longitudinally spaced relation therealong.

The means provided for advancing the auger cutters into the coal seam issimilar to that provided in the old undercutting machines, namely, apower driven winch or drum on each side of the frame and a length ofcable wound up on each drum. Continuous mining during advancement isaccomplished by providing a conveyor on the frame which serves to movethe coal removed from the seam by the auger cutters to the rear end ofthe frame where it can then be conveyed out of the mine by anappropriate conveyor system mounted therein.

Dual auger continuous mining machines of the construction noted abovehave been advanced into the coal seam by sequentially performing twoseparate operations, the first of which is referred to as a sumpingoperation in which the auger cutters are moved generally longitudinallyinto the seam at one side of the face. The second operation is to movethe cutters transversely across the face after sumping has beenaccomplished. As previously indicated, these movements are accomplishedwith the use of the cable and drum assemblies on opposite sides of theframe by anchoring the free ends of the cables at appropriate positionswithin the mine by conventional jacks or the like extendible intoengagement between the mine roof and floor and retractable out of suchengagement. Thus each sumping movement as well as each lateral movementrequired a new cable jack setting. Normal advancement required that thecrew include two jack setters operating quite close to the face and,quite often, close to the cutters themselves.

An object of the present invention is to provide an improved method ofadvancing a continuous miner of the type described into the coal seamwhich eliminates the aforesaid sumping operation and so simplifies theoverall operation as to eliminate the need for the two jack settersheretofore employed.

Another object of the present invention is to provide a machine of thetype described with the capability of advancing in accordance with thisimproved procedure by a simple modification of the existing structurethereof thereby making it possible to achieve the afore said operationaladvantages without substantial increases in manufacturing costs in termsof new equipment and to modify existing machines without substantialretrofit costs.

In accordance with the principles of the present invention theseobjectives are obtained by the simple provision of a pair of jackassemblies on opposite sides of the rear end portion of the continuousminer frame which are extendible into engagement between the mine roofand floor and retractable out of engagement therewith. The provision ofsuch jack assemblies provides the operator with the capability ofrestricting the movement of the frame to a pivotal movement within themine about an axis substantially coincident with an extended one of thejack assemblies and to thereby effect such pivotal movement with the useof a single cable and drum assembly. By mounting the jack assemblies onopposite sides of the frame, this pivotal movement can be alternatelyperformed about automatically properly spaced axes which provide foradvancement in the following manner in a coal seam having a shortwallface extending concavely arcuate from one side wall defining one endthereof to another side wall defining the other end thereof about anaxis spaced outwardly thereof. A complete cycle of operation beginningin such a seam with the continuous miner positioned adjacent one end ofthe arcuate face can be performed in essentially two steps. The firststep is to effect a pivotal movement of the continuous miner across theface to a position adjacent the other end thereof about an axis spacedfrom the axis of the face both in a direction toward the face and inadirection toward the other end thereof to progressively remove asection of coal from the'seam which extends inwardly of the face adistance which increases progressively in the direction of movementacross the face and to progressively define an advanced face whichextends concavely arcuate about the spaced axis of pivotal move ment.The second step is to effect a pivotal movement of the continuous mineracross the advanced face from the other end to a position adjacent theone end about an axis spaced from the axis of said advanced face both ina direction toward the advanced face and in a direction toward the oneend thereof to progressively remove a section of coal from the seamwhich extends inwardly of the advanced face a distance which increasesprogressively in the direction of movement across the advanced face andto progressively define a further advanced face which extends concavelyarcuate about the spaced axis of the last mentioned pivotal movement.

By this procedure, not only is it possible to'obtain a substantialsaving in the time required to complete an operating cycle, but the'cycle can be completed in a simple fashion without the necessity of thetwo jack setters. With the present procedure, no one works forward ofthe pull ropes or cables and the entire crew is able to stay furtherfrom the face and the cutting augers. Furthermore, the cutting cycleprovides for a more rapid movement with a more thorough clean-up andmore uniform conveyor loading throughout the cycle resulting in greatertonage. The semi-circular coal face offers better roof support andventilation. The restricted pivotal movement of the continuous miningmachine presents a much more favorable situation within the mine, sinceonly the front of the machine has substantial movement. This permitspermanent roof supports to be set closer to the face and the use offewer temporary supports during operation.

The procedure can be further simplified from a manual labor standpointby mounting the anchor jacks for the ends of the cables on mobile powerdriven vehicular frames. With this arrangement not only is the normaloperating cycle facilitated, but a greater degree of mobility of themachine is provided when it becomes necessary to move the machine withinthe mine from one operating face to a remote operating face or the like.

These and other objects of the present invention will become moreapparent during thecourse of the following detailed description andappended claims. The invention may best be understood with reference tothe accompanying drawings wherein an illustrative embodiment is shown.

In the drawings:

FIGS. 1A, 1B and 1C are a series of top plan views showing a miningmachine embodying the principles of the present. invention'progressivelyadvancing within a coal mine by the procedures according to the presentinvention;

FIGS. 2A, 2B, 2C, 2D and 2E are views similar to those of FIG. 1illustrating the prior art procedures for advancing a known dual augercontinuous mining machine within a coal. mine;

FIG. 3 is a fragmentary top plan view of the frame of the mining machineillustrating the modifications thereto in accordance with theimprovements of the present invention;

FIG. 4 is a side elevational view of the structure illustrated in FIG.3;

FIG. 5 is an enlarged fragmentary sectional view taken along the line5-5 of FIG. 3;

FIG. 6 is a top plan view of a power driven mobile vehicular frame andanchorjack assembly embodying the principles of the present invention;and

FIG. 7 is a side elevational view of the assembly shown in FIG. 6.

Referring now more particularly to FIG. 1' of the drawings, there isshown therein a continuous mining machine, generally indicated at 10, ofthe dual auger type to which the improvements of the present inventionhave been applied. It will be understood that the principles of thepresent invention have applicability to other types of continuous miningmachines, nevertheless particularly advantageous results are achieved inconjunction with known dual auger type continuous machines, whichinclude the Wilcox MARK and the Jeffrey IOOL, as aforesaid.

The construction and mode of operation of the known Wilcox continuousmining machine is illustrated in FIG. 2, the machine being generallydesignated by the reference character 10'. Since the present inventioninvolves modification of the known machine 10', it is appropriate tofirst describe the basic components of the known machine 10' whichareretained within the machine 10 of the present invention. For presentpurposes corresponding components of the machine 10 of the presentinvention will be indicated by numerals corresponding to primed numeralsof the known machine 10'.

The machine 10 includes a main frame 12' providing a lower surface ofgenerally planar configuration which engages the mine floor so as tosupport the machine thereon. Disposed forwardly of the frame 12' is acoal cutting and conveying mechanism in the form of two auger cutters14'. The auger cutters 14' are oppositely pitched with respect to eachother and are mounted on the frame 12 in forwardly disposed relationwith their axes of rotation extending generally horizontally forwardlyin horizontally spaced parallel relation. The auger cutters 14' aremounted for power driven rotation abouttheir axes in opposite directionsand for independent vertical movement, as by a pivotal action about anaxis parallel to the respective axis of rotation. Each auger cutter 14'includes a pair of helical blades having a series of cutting teeth atthe forward end thereof and a series of cutting teeth extendingoutwardly of the periphery thereof in longitudinally spaced relationtherealong. It will be understood that the machine 10 includes asuitable source of power such as an electric motor which serves toeffect the rotational movement of the augers and that the machine isprovided with hydraulic rams or the like for effecting the independentvertical movement of each auger cutter.

The machine 10' is also provided with means for advancing the augercutters into a coal seam so that the coal engaged by the auger cuttersis loosened from the vein and conveyed outwardly of the face. Theadvancing means, as shown, includes a power driven winch or drum 16 oneach side of the frame 12' and a cable 18' woundaround each drum 16' sothat a free end portion extending from the associated drum andselectively around appropriate forwardly and rearwardly mounted pulleyscan be suitably anchored at its extremity, as by anchor jacks 20'. Eachanchor jack 20 is of conventional construction operable to be extendibleinto engagement between the mine roof and floor and retractable out ofsuch engagement.

The mining machine 10' also includes suitable conveyor means 22' on themain frame 12' for moving the coal removed from the vein by the augercutters M to a position rearwardly of the frame. The coal issuing fromthe rear end of the conveyor means 22' is preferably handled in acontinuous fashion. As shown in FIG. 2, a bridge conveyor assembly,generally indicated at 24', is articulately connected at its forward endto the rearward end of the conveyor means 22' and has its rearward endconnected to a second conveyor assembly 26' which, in the case of theWilcox equipment, is referred to as a Universal Advance Conveyor". Thisconveyor is, in turn, mounted on an extendible floor conveyor assembly,generally indicated at 28 (e.'g. the Wilcox Low-Lo Belt Conveyor). Theconstruction and mode of operation of the overall equipment is disclosedin the aforesaid Wilcox US. Pat. Nos. 3,026,098; 3,282,403; 3,305,268and 3,306,667, all of which are hereby incorporated by reference intothe present specification.

For purposes of the present application it is important to'note the modeof operation of the known machine in order to fully understand andappreciate the improvements thereover which are accomplished bypracticing the principles of the present invention. As

by the use of posts and roof bolts with installation of the latter beingfacilitated by the use of a power driven mobile roof bolting mechanismor assembly 30', which, as shown, is of the type manufactured and soldby the Wilcox Manufacturing Co. under the trade name Wilcox Compact RoofBolter. In the drawings, a roof bolt support is indicated by a squaresymbol, a post support is indicated by a circle within a rectangle, andappropriate temporary support is indicated by a dot within a circle.

For the sake of convenience, the operating cycle may be considered tocommence with the machine It) at a position adjacent one end of theface-as, for example, the left-hand end as shown in FIG. 1A. With themachine in this position, the anchor jacks are set in the position shownwith the cables 18' extending around the rear pulleys. The sumpingoperation is accomplished by actuating the drums 16' to wind up thecables thereon, which has the effect of moving the machinelongitudinally forwardly so that the auger cutters 14' move into thevein with a sumping action. It should be noted that during thisoperation, the auger cutters are each engaging coal throughout the fulldiameter dimension thereof so that there is a relatively high amount ofcoal being moved outwardly of the face during the sumping operation.

After the sumping operation has been completed, the roof boltingmechanism 30' is utilized to install the first roof bolt, as can beclearly seen from FIG. 2B. The next operation is to set the anchor jacks20 in the position substantially as shown in FIG. 2C, which will enableactuation of the drums in opposite directions to effect lateral movementof the machine across the face. The initial lateral movement isperformed in conjunction with an appropriate raising and lowering of theaugers for the purpose of cutting out the full height of the seam at theposition of sumping. This operation is necessary since, during thesumping operation, only two substantially cylindrical cores are removedfrom the vein. This squaring off of the corner" can be accomplished inany desired fashion and normally will entail lateral movement of theentire machine both to the right and then to the left for purposes ofinsuring the best cleanup action. At the end of this operation, thesecond roof bolt is installed as indicated by the position of the roofbolting assembly 30' in FIG. 2C.

In order to complete the lateral movement of the machine across theface, the left hand anchor jack 20' must again be re-set in the positionas shown in FIG. 2D. Prior to the completion of this operation, thethird roof bolt is installed, as indicated by the position of the roofbolting assembly 30' in FIG. 2D. Finally, after moving the assembly 30'back out of the way, the lateral movement of the machine to the right iscompleted and here again, it will be noted that the auger cutters mustbe moved vertically to insure that this corner of the vein is squaredoff.

At the completion of the movement of the machine laterally across theface to the right, the same procedure is then undertaken in the reversedirection to the left across the face to complete a full cycle. Itshould be noted that in the normal operation of the cycle as describedabove, the setting of the roof jacks is accomplished by a worker on eachside of the machine. In almost every instance, the position at which theanchor 5 jacks must be set within the mine is close to the face,

thus subjecting these workers to the hazards of concentrated coal. dustand unsupported roof conditions. Moreover, since the coal which is movedoutwardly of the face by the auger cutters during the sumping operationis conveyed outwardly by full peripheral confinement, whereas the coalmoved outwardly of the face during the movement of the machine acrossthe face is conveyed outwardly without such confinement, the outwardlyconveyed load which must be handled by the conveying means 22 of themachine can vary to a considerable extent during the overall operationdepending upon the rate of movement across the face. Moreover, as thismovement increases an increasing amount of coal is left on the floorinwardly of the face to be picked up by the clean-up scrolls or the nextpass. However, the clean-up scrolls cannot get all of the coal left because of their shorter longitudinal reach. This uneven and incompleteflow of coal to the conveyor means 22 makes it desirable to utilize theanchor jack operators to assist in clean-up by the use of manualshovels.

The apparatus 10 as shown in FIG. lembodies all of the components of themachine 10' as described above. The modifications which are required inaccordance with the principles of the present invention are essentiallyadditional components which can be added to the basic machine. Theseadded components are best shown in FIGS. 3-51 I In FIG. 3, the rear endportion of the frame 12 of the machine 10 is shown. The rear end portionincludes a bottom plate 32 which is shown'in unshaded lines in FIG. 3.This known frame construction 32 is modified in accordance with theprinciples of the present invention by the provision of an extensionbottom plate 34, the forward edge of which is shaped to conform with therear edge of the plate 32 and rigidly attached thereto as by welding orthe like. In order to reduce weight without sacrificing strength whereneeded, the extension plate 34 is provided with a pairof circularopenings 36 in the central portion thereof. Fixed to the rear end of theplate 34 on opposite sides thereof is a pair of vertically extendingrigid sleeves 38. As shown, each of the sleeves 38 is suitably weldedalong its lower edge with the conformingly-shaped rear edge of the plate34 and extends upwardly therefrom. The mounting of each sleeve 38 issuitably reinforced as by an inverted U-shaped strengthening plateconstruction at) welded at its rearward end with the associated sleeveand at its forward end with the upper surface of the plate 32. Eachreinforcing plate construction is likewise welded to the upper surfaceof the extension plate 34.

Each sleeve 38- serves to pivotally support a pivot unit, generallyindicated at 42 which is extensible into engagement between the mineroof and floor and retractable from such engagement. As best shown inFIG. 5, each pivot unit 42 includes a hydraulic ram, generally indicatedat 44, which includes the usual cylinder 46, piston 48 and piston rod5t]. In the embodiment shown, the cylinder 46 includes a longitudinallyextending lug 52 on the exterior periphery thereof within which theinlet and outlet hydraulic passages to the op posite ends of thecylinder pressure chamber are provided. As shown in FIG. 5, thehydraulic ram M is positioned so that the piston rod 50 extendsdownwardly through the cylinder. The lower end of the piston rod 50 isconnected with a floor-engaging member 54 which is loosely disposedwithin an associated sleeve 38. As shown, each floor-engaging member 54is of a generally cup-shaped configuration, having a circular bottomwall 56 and a cylindrical peripheral wall which is longitudinallyslotted, as indicated at 58, to slidably receive the cylinder lug 52.Rigidly secured to the upper surface of the bottom wall 56 is a sleeveor collar 60 of a size to receive the lower end of the piston rod 50.The piston rod is connected with the sleeve as by a pin 62 which extendsthrough registering openings formed transversely through the sleeve andthe rod. The cylindrical wall of the floor-engaging member 54 issuitably apertured to permit installation of the pin.

Each pivot unit 42 also includes a roof-engaging member 64 which, asshown, includes a slotted socket portion 66 on its lower end forengagement over the upper end of the cylinder 46 and an upper portiondefining an upwardly facing roof-engaging conical surface 68.

It will be understood that a source of hydraulic fluid under pressurecarried by the machine frame is communicated with each hydraulic ram 44so as to be controlled by the operator. This entails extending a pair ofhydraulic lines 70 and 72 to each hydraulic ram. In order to prevent anunlimited relative rotational movement of each pivot unit 42 withrespect to the associated mounting sleeve 38 thereof, which might resultin the entanglement or fouling of the hydraulic lines 70 and 72,suitable rotational stop means is provided. in the embodiment shown, itwill be noted that the engagement of the cylinder lug 52 within theslots of the members 54 and 64 serves to prevent relative rotationalmovement between the hydraulic ram 44 and the members 54 and 64 whilepermitting relative vertical movement therebetween. Since the members 54and 64 are effectively rotationally keyed to the hydraulic ram 44,provision of suitable stop means on either of the members 54 or 64 withrespect to the associated sleeve 38 or frame part 34 will serve toeffectively limit the rotational movement of each pivot unit 42. In theembodiment shown, the stop means for each pivot unit 42 comprises a post74 rigidly secured to the exterior periphery of each sleeve 38 andextending upwardly therefrom. Formed on the upper exterior periphery ofeach floor engaging member 54 is an arcuate stop element 76, havingradial ends 78 adapted to engage the associated post 74.

It will be understood that the pivot units 42 thus provided on oppositesides of the rear end portion of the frame of the machine 10cooperatively function with the drums and cables 16 and 18 on each sideof the frame as the advancing means for the machine. This ad vancingmeans enables the machine to be operated in accordance with the methodof the present invention in a manner which eliminates the sumping actionheretofore required and permits a complete cycle of operation with asimple two-step procedure. The first step is to effect a pivotalmovement of the continuous miner across the face to a position adjacentthe other end thereof about an axis spaced from the axis of the faceboth in a direction toward the face and in a direction toward the otherend thereof to progressively remove a section of coal from the seamwhich extends inwardly of the face a distance which increasesprogressively in the direction of movement across the face and toprogressively define an advanced face which extends concavely arcuateabout the spaced axis of pivotal movement. The second step is to effecta pivotal movement of the continuous miner across the advanced face fromthe other end to a position adjacent the one end about an axis spacedfrom the axis of said advanced face both in a direction toward theadvanced face and in a direction toward the'one end thereof toprogressively remove a section of coal from the seam which extendsinwardly of the advanced face a distance which increases progressivelyin the direction of movement across the advanced face and toprogressively define a further advanced face which extends concavelyarcuate about the spaced axis of the last mentioned pivotal movement.

A specific example of the cycle of operation embodied in theabove-identified method utilizing the machine 10 of the presentinvention is illustrated in FIG. 1. It will be understood that thecomponents which comprise the advancingmeans as previously indicatedareutilized with anchor jacks of the type described with respect to theknown machine 10'. However, the

apparatus and procedure illustrated in FIG. 1 includes the provision ofa pair of power driven mobile jack assemblies, generally indicated at80, which are utilized in lieu of the known anchor jacks described inconnection with the structure and operation of the known machine 10.Consequently, before proceeding with the description of the operation asillustrated in FIG. 1 it is first appropriate to obtain an understandingof the construction and operation of the assemblies 80, a preferredembodiment of which is illustrated in FIGS. 6 and 7.

ln general, it can be stated that each power driven mobile jack assemblyis constructed in a manner similar to the Wilcox Compact Roof Bolterpreviously described and indicated in FIG. 2 by the numeral 30'. Thus,as shown, each assembly 80 includes a main frame, generally indicated at82, which has mounted on opposite sides of the central portion thereof apair of gear case assemblies 84, each of which is drivinglyconnectedwith apair of longitudinally aligned front and rear wheels 86 and 88.Each gear case assembly 84 is adapted to be driven by a hydraulic motor,generally indicated at 90, and each hydraulic motor is, in turn, drivenby a hydraulic pump, generally indicated at 92 (see FIG. 6). Thehydraulic pump 92 is, in turn, driven by an electrical motor 94 inaccordance with conventional practice.

Mounted on the frame 82 toward the rear end thereof are suitable controlvalve actuators 96 which can be manually moved by the operator for thepurpose of controlling the forward and rearward movement of the framethrough desired movement of the wheels 86 and 88 by the gearcaseassemblies 84 and hydraulic motors 90. The arrangement as shown is afour wheel drive assembly in which turning of the vehicle frame isaccomplished by actuation of the controls 86 in generally conventionalfashion.

The vehicle frame 82 includes a pair of transversely spaced forwardlyextending anchor jack mounting plates 98. The mounting plates 98 serveto operatively receive and support an anchor jack assembly, generallyindicated at 100, which is constructed in a manner similar to the pivotunits 42 previously described. Thus, each assembly 100 includes ahydraulic ram 102, a floor-engaging member 104 and a roof-engagingmemher 106. The arrangement differs from that previously described inthat the unit is mounted on the plates 98 by a collar 108 which engagesover the central portion of the cylinder of the hydraulic ram 102 andhas a pair of trunions 110 extending radially outwardly therefrom atdiametrically opposed positions for engagement within upwardly extendingopenings 112 formed in the upper surface of the mounting plates 98. Inaddition, a collar 114 is swivelly mounted on the lower exteriorperiphery of the floor engaging member 104-. The swivel collar 114 isprovided with a hook 116 for receiving the end of the cable 18associated therewith.

Referring now more particularly to FIG. 1, the cycle of operation willbe conveniently begun with the machine 10 positioned adjacent one end ofa previously formed face, indicated at F1 in FIG. 1A. It will be notedthat the face F1 is generally arcuate in configuration about an axisindicated at A1 which is coincident with the axis of the left-hand pivotunit 4-2 with the machine in the position as shown in FIG. 1A. It willbe under-- stood that the position as shown in FIG. 1A is the positionthe machine assumes at the end of a preceding cycle. The free ends ofthe respective cables 18 are connected with the respective swivel hooks116 of the respective assemblies 80. The left-hand auger cutter 14 isnormally disposed in a raised position at the end of this cycle and theright-hand auger cutter 14 is disposed in a lowered position adjacentthe floor. Thus, there is a ledge of coal which extends from the innerperiphery of the right-hand auger cutter to the side wall of the entrybeing formed below the periphery of the lefthand auger cutter.

Operation is commenced by disengaging the drive to the right-hand drum16 and moving the assembly 80 adjacent the right-hand side wall to theposition as shown in FIG. 1A and then actuating the anchor jack assembly100 thereof to extend the same into engagement between the mine roof andfloor. Next, the operator of the machine actuates the appropriatecontrols to disengage the left-hand drum 16 and to engage the right-handdrum 16. Either after this operation has been completed, or before, theoperator of the machine actuates the appropriate controls to extend therighthand pivot unit $2 and retract the left-hand pivot unit 42.

It will be noted that the extension of the right-hand pivot unit 42 nowrestricts the movement of the entire machine about a pivotal axis A2coincident with the axis of the right-hand pivot unit, which is spacedfrom the axis All of the face F1 both in a direction laterally towardthe right-hand side wall of the entry being formed and in a directiontoward the face Fl. Prior to the actuation of the right-hand drum 16 tocommence the pivotal movement of the machine, the right-hand augercutter 14 which was previously in a lowered position is raised so as toengage the roof of the mine seam and the left-hand auger is lowered to aposition adjacent the floor. Actuation of the right-hand drum 16 to windup the cable will now effect a pivotal movement of the entire machineabout the axis A2 in a clockwise direction as viewed in FIG. 1, ortoward the right, during which movement the left-hand cable 18 isallowed to pay out from the disengaged left-hand drum 16. It will benoted that during the initial portion of this movement the left-handauger cutter 141 will cut the ledge of coal adjacent the left-hand sidewall and the loose coal beyond the ledge which was previously leftduring the latter cycle of operation. As the machine is moved arcuatelyacross the face F1, the cutters move inwardly of the face a distancewhich progressively increases as the arcuate movement progresses. Whenthe machine has reached the opposite side wall, as shown in FIG. 18, asection of coal has been removed from the seam outwardly of the face F1which is substantially arcuately wedge-shaped in configuration and a newface F2 is defined which is generally arcuate about the axis A2. Hereagain, a ledge of coal is left below the righthand auger cutterextending from the right-hand side wall to the righthand periphery ofthe left-hand auger cutter.

When the machine 10 reaches the position as shown in FIG. 1B, the firststep of the cycle is completed and the jack assembly of the left-handassembly 8h is retracted so that the latter can be moved into theposition shown in FIG. 1C, at which position, the jack as sembly 100thereof is again extended into engagement between the mine roof andfloor. The operator of the machine then actuates the hydraulic controlsto retract the right-hand pivot unit 42 and to extend the left-handpivot unit 42 into engagement between the mine roof and floor. Thismovement establishes an axis A3 of pivotal movement of the machineduring the second step which is spaced laterally and toward the face F2from the axis A2. As before, the vertical position of the auger cutters14 is reversed, that is, the left-hand auger is moved from a loweredposition to a raised position and the right-hand auger cutter is movedfrom a raised position to a lowered position. The left-hand drum 16 isthen engaged and actuated to commence movement of the machine in acounter-clockwise direction as viewed in FIG. 1B, or the left, duringwhich movement the right-hand cable 18 is allowed to pay out from thedisengaged right-hand drum 16. Here again, during the initial movement,the'lowered right-hand auger M removes the coal in the ledge which hasbeen previously left and as the machine 10 proceeds across the face asection of coal is removed from the seam which extends inwardly of theface F2 a distance which progressively increases as the arcuate movementto the left proceeds. As soon as the machine reaches the left-hand endwall, the cycle of operation is completed and here again, it will benoted that movement of the machine across the face to the left hasremoved asection of coal which is of generally arcuate wedge-shapedconfiguration and defines a new arcuate face, F3, which is arcuate aboutthe axis A3.

There are many significant advantages which are achieved by advancingthe machine 10 in accordance with the principles of the present methodutilizing the modified structure of the present apparatus as previouslydescribed in comparison with the known method of advancing the knownmachine 111. At the outset, it will be recognized that the procedure andapparatus for advancingin accordance with the present invention has theeffect of creating an arcuate face in the coal seam. It is known thatsuch a face configuration provides a more favorable roof support than isthe case with relatively straight faces. Moreover, as can be clearlyseen from the illustrations contained in FIG. 1, no personnel arerequired to work in close proximity to the face or the cutting mechanismof the machine, as is the case with the known procedure. This enablesoperation without the necessity of providing roof support near the faceand, of course, provides the further advantage of eliminating the needto subject workers to the inherent dangers which exist close to theface, such as concentrated coal dust and falling rock from the roof.Moreover, the arcuate configuration of the face is advantageous from thestandpoint of air circulation in comparison with straight faces.

All of these advantages make it possible to advance the machine withoutthe need of providing two separate anchor jack workers, such as waspreviously required in the operation of the machine 10. The roof boltingoperation can be carried on at a. position outwardly of the face towardthe rear end of the machine and this worker can also operate theassemblies 80. Moreover, the operation of the machine is greatlysimplified since the elimination of the sumping operation eliminates thenecessity of the operator to square off the corners which was previouslyrequired. This operation is automatically accomplished during thepresent operating cycle in a manner described above. More over, thisarrangement makes the flow of coal to the conveyor 22 of the machinemuch more uniform than was the case during the operating cycle of theknown machine 10'. Finally, it will be noted that the rear end of themachine frame 12 does not have the same degree of movement as is thecase with the machine 10. In this regard, however, it will be noted thatthe machine 10 is still fully capable of being operated in the samefashion as the known machine 10'. In summary, it can be stated that byutilizing the principles of the present invention a much more rapidrecovery of coal can be obtained with less labor than heretoforerequired with a much more uniform flow of coal during the operation andwith less clean-up required. Indeed, by utilizing the principles of thepresent invention the clean-up problem is sufficiently alleviated as toeliminate the need for any manual clean-up in the face area.

It will be understood that the position of the pivot units 42 on themachine frame 12 serve to automatically establish both the axis ofpivotal movement across the face and the next axis of movement upon thecompletion of the first movement. The cable and drum arrangement foreffecting the pivotal movement is preferred but other means may beutilized. Moreover, with the use of the cable and drum assemblies it ispossible to effect a plurality of operating cycles without advancing theanchor settings, as indicated above.

It thus will be seen that the objects of this invention have been fullyand effectively accomplished. It will be realized, however, that theforegoing preferred specific embodimenthas been shown and described forthe purpose of illustrating the functional and structural principles ofthis invention and is subject to change without departure from suchprinciples. Therefore, this invention includes all modificationsencompassed within the spirit and scope of the following claims.

What is claimed is:

1. A continuous mining machine for removing coal from a coal seam havinga shortwall face extending concavely arcuate from a side wall definingone end thereof to another side wall defining the other end thereofabout an axis spaced outwardly thereof, said machine comprising:

a. an elongated frame,

b. power driven cutting and conveying means carried by said frame inforwardly disposed relation thereto and operable during relativemovement of said frame with respect to said face to cut a room sectionin the coal seam inwardly of the face thereof while continuouslyconveying the cut coal outwardly of the face,

0. conveyor means operatively associated with said frame forcontinuously moving the coal rearwardly away from the mine face which iscut and conveyed outwardly of the mine face during the formation of saidroom section by said cutting and conveying means,

d. first means for effecting a pivotal movement of said frame and saidcutting and conveying means from a position adjacent one end of saidface across the face to a position adjacent the other end thereof aboutan axis adjacent the rear portion of the frame spaced from the axis ofthe face both in a direction toward the face and in a direction towardsaid other end thereof to progressively remove a section of coal fromthe seam which extends inwardly of the face a distance which increasesprogressively'in the direction of movement across the face and toprogressively define an adv anced face which extends concavely arcuateabout said spaced axis of pivotal movement, and

e. second means for effecting a pivotal movement of said frame and saidcutting and conveying means acrossthe advanced face from said other endto a position adjacent said one end about an axis adjacent the rearportion of the frame spaced from the axis of said advanced face both ina direction toward the advanced face and in a-direction toward said oneend thereof to progressively remove a section of coal from the seamwhich extends inwardly of the advanced face a distance which increasesprogressively in the direction of movement across the advanced face andto progressively define a further advanced face which extends concavelyarcuate about the spaced axis of the last mentioned pivotal movement,

said first pivotal movement effecting means including a first verticallyextensible and retractable pivot unit carried by the rear end portion ofsaid frame at the side thereof adjacent the other end of said face forextensible engagement between the mine roof and floor and retractabledisengagement between the mine roof and floor, said second pivotalmovement effecting means including a second vertically extensible andretractable pivot unit carried by the rear end portion of said frame atthe side thereof adjacentthe one end of said face for extensibleengagement between the mine roof and floor and retractable disengagementbetween the mine roof and floor.

2. A continuous mining machine as defined in claim 1 wherein each ofsaid pivot units includes a hydraulic ram.

3. A continuous mining machine as defined in claim 2 wherein each ofsaid pivot units includes an annular floor engaging member, a verticallyextending sleeve fixed to said frame receiving said floor engagingmember for limited vertical movement and limited pivotal movement withrespect thereto, and a roof engaging member, said hydraulic ramincluding a piston rod connected at its lower end to said floor engagingmember and a cylinder mounted for non-rotating vertical movement withrespect to said floor engaging member and connected at its upper end tosaid roof engaging member.

cludes a second power driven drum on the side of the frame adjacent saidsecond pivot unit, and a second length of cable wound around said seconddrum and having an end portion extending therefrom adapted to beanchored adjacent the other end of said face.

5. A continuous mining machine as defined in claim 4 wherein said firstpivotal movement effecting means further includes a first anchoring unitextensible for engagement between the mine roof and floor andretractable for disengagement between the mine roof and floor and meansconnecting the end portion of said first cable with said first anchoringunit and wherein said second pivotal movement effecting means furtherincludes a second anchoring unit extensible for engagement between themine roof and floor and retractable for disengagement between the mineroof and floor and means connecting said second cable with said secondanchoring unit.

6. A continuous mining machine as defined in claim S-Wherein each ofsaid anchoring units is mounted on a mobile power driven vehicle.

7. A continuous mining machine as defined in claim 6 wherein saidcutting and conveying means comprises a pair of oppositely pitched augercutters, each including a pair of longitudinally spaced helical bladeshaving cutting means disposed adjacent the forward end thereof andcutting teeth extending outwardly of the longitudinal periphery of saidblades in longitudinally spaced relation, and means mounting said augercutters for rotational movement in opposite directions abouttransversely spaced generally horizontally extending axes and forindependent vertical movement.

8. Method of advancing a continuous miner of the type including a pairof horizontally spaced vertically movable oppositely pitched andoppositely rotatable auger cutters in a coal seam having a shortwallface extending concavely arcuate from one side wall defining one endthereof to another side wall defining the other end thereof about anaxis spaced outwardly "thereof which comprises the steps of positioningthe continuous miner adjacent one and of the arcuate face of the coalseam with the auger cutters adjacent said one end in a lowered positionand the other auger cutter in a raised position, effecting a pivotalmovement of the continuous miner with said auger cutters maintainedsubstantially in said positions across the face to a position adjacentthe other end thereof about an axis spaced from the axis of the faceboth in a direction toward the face and in a direction toward said otherend thereof, while continuously rotating said auger cutters in oppositedirections to establish-cutting actions of the raised and lowered augercutters directed respectively downwardly and upwardly and conveyingactions directed respectively outwardly and in a direction opposed tosaid direction of pivotal movement and outwardly and in the direction ofpivotal movement to thereby (l) progressively remove a section of coalfrom the seam which extends inwardly of the face a distance which increases progressively in the direction of movement across the faceexcept for a bottom ledge adjacent said other side wall which is left byvirtue of the leading relationship of the raised auger and the trailingrelationship of the lowered auger cutter and (2) progressively define anadvanced face which extends concavely arcuate about said spaced axis ofpivotal movement except for the portion of the face defined by saidbottom ledge,-

effecting vertical movements of said auger cutters such that the raisedauger cutter is in a lowered position and the lowered auger cutter is ina raised position,

effecting a pivotal movement of the continuous -miner with the augercutters maintained substantially in their positions of verticalmovement, as aforesaid, across the advanced face from said other end toa position adjacent said one end about an axis spaced by the axis ofsaid advanced face both in a direction toward the advanced face and in adirection toward said one end thereof while continuously rotating saidauger cutters in opposite directions to establish cutting actions by theraised and lowered auger cutters directed respectively downwardly andupwardly and conveying actions directed respectively outwardly and in adirection opposed to the direction of the last mentioned pivotalmovement and outwardly and in a direction of the last mentioned pivotalmovement to thereby (l) progressively remove said bottom ledge by thecutting and conveying action of said lowered auger cutter, (2)progressively remove a section of coal from the seam which extendsinwardly of the advanced face a distance which increases progressivelyin the direction of movement across the ad vanced face except for abottom ledge adjacent said one side wall which is left by virtue of theleading relationship of the raised auger and the trailing relationshipof the lowered auger cutter and (3') progressively define a furtheradvanced face which extends concavely arcuate about the spaced axis ofthe last mentioned pivotal movement except for the face portion definedby said bottom ledge.

9. A continuous mining machine for removing coal from a coal seam havinga shozrtwall face extending concavely arcuate from a side wall definingone end thereof to another side wall defining the other end thereofabout an axis spaced outwardly thereof, said machine comprising:

a. an elongated frame, I

b. a pair of oppositely pitched auger cutters, each including a pair oflongitudinally spaced helical blades having cutting means disposedadjacent the forward end thereof and cutting teeth extending outwardlyof the longitudinal periphery of said blades in longitudinally spacedrelation,

c. means mounting said auger cutters on said frame in forwardly disposedrelation thereto for rotational movement in opposite directions abouttransversely spaced generally horizontally extending axes and forindependent vertical movement,

d. means carried by said frame for rotating said auger cutters in saidopposite directions,

e. means carried by said frame for effecting vertical movement of eachof said auger cutters between raised and lowered positions,

f. first means for effecting a pivotal movement of said frame with saidauger cutters maintained substantially in said positions across the faceto a position adjacent the other end thereof about an axis spaced fromthe axis of the face both in a direction toward the face and in adirection toward said other end thereof with said auger cutters rotatingin opposite directions to establish cutting actions of the raised andlowered auger cutters directed respectively downwardly and upwardly andconveying actions directed respectively outwardly and in a directionopposed to said direction of pivotal movement and outwardly and in thedirection of pivotal movement to thereby (l) progressively remove asection of coal from the seam which extends inwardly of the face adistance which increases progressively in the direction of movementacross the face except for a bottom ledge adjacent said other side wallwhich is left by virtue of the leading relationship of the raised augerand the trailing relationship of the lowered auger cutter and (2)progressively define an advanced face which extends concavely arcuateabout said'spaced axis of pivotal movement except for the portion of theface defined by said bottom ledge,

g. second means for effecting a pivotal movement of the continuous minerwith said auger cutters maintained substantially in reversed. raised andlowered positions across the advanced face from said other end to aposition adjacent said one end about an axis spaced by the axis of saidadvanced face both in a direction toward the advanced face and in adirection toward said one end thereof with said auger cutters rotatingin opposite directions to establish cutting actions by the raised andlowered auger cutters directed respectively downwardly and upwardly andconveying actions directed respectively outwardly and in a directionopposed to the direction of the last mentioned pivotal movement andoutwardly and in the direction of the last mentioned pivotal movement tothereby (l) progressively remove said bottom ledge by the cutting andconveying action of said lowered auger cutter, (2) progressively removea section of coal from the seam which extends inwardly of the advancedface a distance which increases progressively in the direction ofmovement across the advanced face except for a bottom ledge adjacentsaid one side wall which is left by virtue of the leading relationshipof the raised auger and the trailing relationship of the lowered augercutter and (3) progressively define includes a first mobile power drivenvehicle having a first anchoring unit extensible for engagement betweenthe mine roof and floor and retractable for disengagement between themine roof and floor and wherein said second pivotal movement effectivemeans includes a second mobile power driven vehicle having a secondanchoring unit extensible for engagement between the mine roof and floorand retractable for disengagement between the mine roof and floor.

11. A continuous mining machine as defined in claim 9 wherein said firstpivotal movement effecting means further includes a first power drivendrum on the side of the frame adjacent said first pivot unit, and afirst length of cable wound around said first drum and having an endportion extending therefrom adapted to be anchored adjacent the one endof said face and said second pivotal movement effecting means furtherincludes a second power driven drum on the side of the frame adjacentsaid second pivot unit, and a second length of cable wound around saidsecond drum and having an end portion extending therefrom adapted to beanchored adjacent the other end of said face.

12. A continuous mining machine as defined in claim 11 wherein saidfirst pivotal movement effecting means further includes a firstanchoring unit extensible for engagement between the mine roof and floorand retractable for disengagement between the mine roof and floor meansconnecting the end portion of said first cable with said first anchoringunit and wherein said second pivotal movement effecting means furtherincludes a second anchoring unit extensible for engagement between themine roof and floor and retractable for disengagement between the mineroof and floor and means connecting said second cable with said second 7anchoring unit.

13. A continuous mining machine as defined in claim

1. A continuous mining machine for removing coal from a coal seam havinga shortwall face extending concavely arcuate from a side wall definingone end thereof to another side wall defining the other end thereofabout an axis spaced outwardly thereof, said machine comprising: a. anelongated frame, b. power driven cutting and conveying means carried bysaid frame in forwardly disposed relation thereto and operable duringrelative movement of said frame with respect to said face to cut a roomsection in the coal seam inwardly of the face thereof while continuouslyconveying the cut coal outwardly of the face, c. conveyor meansoperatively associated with said frame for continuously moving the coalrearwardly away from the mine face which is cut and conveyed outwardlyof the mine face during the formation of said room section by saidcutting and conveying means, d. first means for effecting a pivotalmovement of said frame and said cutting and conveying means from aposition adjacent one end of said face across the face to a positionadjacent the other end thereof about an axis adjacent the rear portionof the frame spaced from the axis of the face both in a direction towardthe face and in a direction toward said other end thereof toprogressively remove a section of coal from the seam which extendsinwardly of the face a distance which increases progressively in thedirection of movement across the face and to progressively define anadvanced face which extends concavely arcuate about said spaced axis ofpivotal movement, and e. second means for effecting a pivotal movementof said frame and said cutting and conveying means across the advancedface from said other end to a position adjacent said one end about anaxis adjacent the rear portion of the frame spaced from the axis of saidadvanced face both in a direction toward the advanced face and in adirection toward said one end thereof to progressively remove a sectionof coal from the seam which extends inwardly of the advanced face adistance which increases progressively in the direction of movementacross the advanced face and to progressively define a further advancedface which extends concavely arcuate about the spaced axis of the lastmentioned pivotal movement, said first pivotal movement effecting meansincluding a first vertically extensible and retractable pivot unitcarried by the rear end portion of said frame at the side thereofadjacent the other end of said face for extensible engagement betweenthe mine roof and floor and retractable disengagement between the mineroof and floor, said second pivotal movement effecting means including asecond vertically extensible and retractable pivot unit carried by therear end portion of said frame at the side thereof adjacent the one endof said face for extensible engagement between the mine roof and floorand retractable disengagement between the mine roof and floor.
 2. Acontinuous mining machine as defined in claim 1 wherein each of saidpivot units includes a hydraulic ram.
 3. A continuous mining machine asdefined in claim 2 wherein each of said pivot units includes an annularfloor engaging member, a vertically extending sleeve fixed to said framereceiving said floor engaging member for limited vertical movement andlimited pivotal movement with respect thereto, and a roof engagingmember, said hydraulic ram including a piston rod connected at its lowerend to said floor engaging member and a cylinder mounted fornon-rotating vertical movement with respect to said floor engagingmember and connected at its upper end to said roof engaging member.
 4. Acontinuous mining machine as defined in claim 3 wherein said firstpivotal movement effecting means further includes a first power drivendrum on the side of the frame adjaCent said first pivot unit, and afirst length of cable wound around said first drum and having an endportion extending therefrom adapted to be anchored adjacent the one endof said face and said second pivotal movement effecting means furtherincludes a second power driven drum on the side of the frame adjacentsaid second pivot unit, and a second length of cable wound around saidsecond drum and having an end portion extending therefrom adapted to beanchored adjacent the other end of said face.
 5. A continuous miningmachine as defined in claim 4 wherein said first pivotal movementeffecting means further includes a first anchoring unit extensible forengagement between the mine roof and floor and retractable fordisengagement between the mine roof and floor and means connecting theend portion of said first cable with said first anchoring unit andwherein said second pivotal movement effecting means further includes asecond anchoring unit extensible for engagement between the mine roofand floor and retractable for disengagement between the mine roof andfloor and means connecting said second cable with said second anchoringunit.
 6. A continuous mining machine as defined in claim 5 wherein eachof said anchoring units is mounted on a mobile power driven vehicle. 7.A continuous mining machine as defined in claim 6 wherein said cuttingand conveying means comprises a pair of oppositely pitched augercutters, each including a pair of longitudinally spaced helical bladeshaving cutting means disposed adjacent the forward end thereof andcutting teeth extending outwardly of the longitudinal periphery of saidblades in longitudinally spaced relation, and means mounting said augercutters for rotational movement in opposite directions abouttransversely spaced generally horizontally extending axes and forindependent vertical movement.
 8. Method of advancing a continuous minerof the type including a pair of horizontally spaced vertically movableoppositely pitched and oppositely rotatable auger cutters in a coal seamhaving a shortwall face extending concavely arcuate from one side walldefining one end thereof to another side wall defining the other endthereof about an axis spaced outwardly thereof which comprises the stepsof positioning the continuous miner adjacent one and of the arcuate faceof the coal seam with the auger cutters adjacent said one end in alowered position and the other auger cutter in a raised position,effecting a pivotal movement of the continuous miner with said augercutters maintained substantially in said positions across the face to aposition adjacent the other end thereof about an axis spaced from theaxis of the face both in a direction toward the face and in a directiontoward said other end thereof, while continuously rotating said augercutters in opposite directions to establish cutting actions of theraised and lowered auger cutters directed respectively downwardly andupwardly and conveying actions directed respectively outwardly and in adirection opposed to said direction of pivotal movement and outwardlyand in the direction of pivotal movement to thereby (1) progressivelyremove a section of coal from the seam which extends inwardly of theface a distance which increases progressively in the direction ofmovement across the face except for a bottom ledge adjacent said otherside wall which is left by virtue of the leading relationship of theraised auger and the trailing relationship of the lowered auger cutterand (2) progressively define an advanced face which extends concavelyarcuate about said spaced axis of pivotal movement except for theportion of the face defined by said bottom ledge, effecting verticalmovements of said auger cutters such that the raised auger cutter is ina lowered position and the lowered auger cutter is in a raised position,effecting a pivotal movement of the continuous miner with the augercutters maintained substantially in their positions of verTicalmovement, as aforesaid, across the advanced face from said other end toa position adjacent said one end about an axis spaced by the axis ofsaid advanced face both in a direction toward the advanced face and in adirection toward said one end thereof while continuously rotating saidauger cutters in opposite directions to establish cutting actions by theraised and lowered auger cutters directed respectively downwardly andupwardly and conveying actions directed respectively outwardly and in adirection opposed to the direction of the last mentioned pivotalmovement and outwardly and in a direction of the last mentioned pivotalmovement to thereby (1) progressively remove said bottom ledge by thecutting and conveying action of said lowered auger cutter, (2)progressively remove a section of coal from the seam which extendsinwardly of the advanced face a distance which increases progressivelyin the direction of movement across the advanced face except for abottom ledge adjacent said one side wall which is left by virtue of theleading relationship of the raised auger and the trailing relationshipof the lowered auger cutter and (3) progressively define a furtheradvanced face which extends concavely arcuate about the spaced axis ofthe last mentioned pivotal movement except for the face portion definedby said bottom ledge.
 9. A continuous mining machine for removing coalfrom a coal seam having a shortwall face extending concavely arcuatefrom a side wall defining one end thereof to another side wall definingthe other end thereof about an axis spaced outwardly thereof, saidmachine comprising: a. an elongated frame, b. a pair of oppositelypitched auger cutters, each including a pair of longitudinally spacedhelical blades having cutting means disposed adjacent the forward endthereof and cutting teeth extending outwardly of the longitudinalperiphery of said blades in longitudinally spaced relation, c. meansmounting said auger cutters on said frame in forwardly disposed relationthereto for rotational movement in opposite directions abouttransversely spaced generally horizontally extending axes and forindependent vertical movement, d. means carried by said frame forrotating said auger cutters in said opposite directions, e. meanscarried by said frame for effecting vertical movement of each of saidauger cutters between raised and lowered positions, f. first means foreffecting a pivotal movement of said frame with said auger cuttersmaintained substantially in said positions across the face to a positionadjacent the other end thereof about an axis spaced from the axis of theface both in a direction toward the face and in a direction toward saidother end thereof with said auger cutters rotating in oppositedirections to establish cutting actions of the raised and lowered augercutters directed respectively downwardly and upwardly and conveyingactions directed respectively outwardly and in a direction opposed tosaid direction of pivotal movement and outwardly and in the direction ofpivotal movement to thereby (1) progressively remove a section of coalfrom the seam which extends inwardly of the face a distance whichincreases progressively in the direction of movement across the faceexcept for a bottom ledge adjacent said other side wall which is left byvirtue of the leading relationship of the raised auger and the trailingrelationship of the lowered auger cutter and (2) progressively define anadvanced face which extends concavely arcuate about said spaced axis ofpivotal movement except for the portion of the face defined by saidbottom ledge, g. second means for effecting a pivotal movement of thecontinuous miner with said auger cutters maintained substantially inreversed raised and lowered positions across the advanced face from saidother end to a position adjacent said one end about an axis spaced bythe axis of said advanced face both in a direction toward the advancedface And in a direction toward said one end thereof with said augercutters rotating in opposite directions to establish cutting actions bythe raised and lowered auger cutters directed respectively downwardlyand upwardly and conveying actions directed respectively outwardly andin a direction opposed to the direction of the last mentioned pivotalmovement and outwardly and in the direction of the last mentionedpivotal movement to thereby (1) progressively remove said bottom ledgeby the cutting and conveying action of said lowered auger cutter, (2)progressively remove a section of coal from the seam which extendsinwardly of the advanced face a distance which increases progressivelyin the direction of movement across the advanced face except for abottom ledge adjacent said one side wall which is left by virtue of theleading relationship of the raised auger and the trailing relationshipof the lowered auger cutter and (3) progressively define a furtheradvanced face which extends concavely arcuate about the spaced axis ofthe last mentioned pivotal movement except for the face portion definedby said bottom ledge, and h. conveyor means operatively associated withsaid frame for continuously moving the coal rearwardly away from themine face which is removed from the mine face during the formation ofsaid room sections by said auger cutters.
 10. A continuous miningmachine as defined in claim 9 wherein said first pivotal movementeffecting means includes a first mobile power driven vehicle having afirst anchoring unit extensible for engagement between the mine roof andfloor and retractable for disengagement between the mine roof and floorand wherein said second pivotal movement effective means includes asecond mobile power driven vehicle having a second anchoring unitextensible for engagement between the mine roof and floor andretractable for disengagement between the mine roof and floor.
 11. Acontinuous mining machine as defined in claim 9 wherein said firstpivotal movement effecting means further includes a first power drivendrum on the side of the frame adjacent said first pivot unit, and afirst length of cable wound around said first drum and having an endportion extending therefrom adapted to be anchored adjacent the one endof said face and said second pivotal movement effecting means furtherincludes a second power driven drum on the side of the frame adjacentsaid second pivot unit, and a second length of cable wound around saidsecond drum and having an end portion extending therefrom adapted to beanchored adjacent the other end of said face.
 12. A continuous miningmachine as defined in claim 11 wherein said first pivotal movementeffecting means further includes a first anchoring unit extensible forengagement between the mine roof and floor and retractable fordisengagement between the mine roof and floor means connecting the endportion of said first cable with said first anchoring unit and whereinsaid second pivotal movement effecting means further includes a secondanchoring unit extensible for engagement between the mine roof and floorand retractable for disengagement between the mine roof and floor andmeans connecting said second cable with said second anchoring unit. 13.A continuous mining machine as defined in claim 12 wherein each of saidanchoring units is mounted on a mobile power driven vehicle.